Evidence linking calcium to increased organo-mineral association in soils

• DOI: 10.1007/s10533-021-00779-7
• Publication Date: 2021-04-04T14:02:26Z
• Authors: Mike C. Rowley; Stephanie Grand; Jorge E. Spangenberg; Eric P. Verrecchia
• Keywords: Soil carbon

Geochemical indicators are emerging as important predictors of soil organic carbon (SOC) dynamics, but evidence concerning the role calcium (Ca) is scarce. This study investigates Ca prevalence in SOC accumulation by comparing otherwise similar sites with (CaCO3-bearing) or without carbonates (CaCO3-free). We measured content and matter quality (C stable isotope composition, expressed δ13C values, thermal stability) bulk samples. then used sequential sonication density fractionation (DF) to separate two occluded pools from free mineral-associated SOC. The content, mass, values were determined all fractions. X-ray photoelectron spectroscopy was investigate surface chemistry selected Our hypothesis that occlusion would be more prevalent at CaCO3-bearing site due influence on aggregation, inhibiting oxidative transformation, preserving lower values. Bulk twice high profiles, which also had Yet, contrary our hypothesis, only accounted for a small proportion total (< 10%). Instead, it heavy fraction (HF), containing C, majority Overall, an increased associated near-doubling content. Future investigations should now aim isolate Ca-mediated complexation processes increase organo-mineral association preserve values.The online version this article (10.1007/s10533-021-00779-7) contains supplementary material, available authorized users.